RAPID: Impacts of Hurricane Maria on tropical forest biogeochemistry: short-term response and long-term trajectory

这项研究将研究飓风玛丽亚对热带森林和排干热带森林的溪流中有机碳和养分动态的直接影响，以更好地确定短期影响如何在单一和反复干扰后影响森林和水资源的长期轨迹。飓风玛丽亚造成广泛的树冠破坏和土壤表面和波多黎各卢基洛实验森林(LEF)内的溪流渠道的垃圾沉积。了解植物碎屑中的有机碳、磷和氮在通过土壤和进入溪流的过程中是如何被修改的，包括与大气的任何交换，对于确定生态系统对干扰的长期反应至关重要。作为该项目的一部分进行的这项研究将为LEF生态系统的弹性和抵抗力提供见解，该生态系统是美国国家森林系统中埃尔云克国家森林的一部分。PI团队将与波多黎各的科学家和学生密切合作，促进当地学生和教师的研究需求。研究人员将把项目成果纳入以气候变化对陆地生态系统的影响为中心的介绍和外联活动组合中。该项目将支持波多黎各学生作为实验室人员，为其他拉美裔学生和博士后科学家提供培训，并通过外联和辅导活动促进科学中的性别平等，从而促进科学多样性。这项研究利用了先前存在的飓风模拟实验，使研究人员能够检验关于单一和反复飓风干扰对生态系统过程的影响的假说，包括通过土壤剖面和微生物活动对碳和养分的生物地球化学转移，以应对基质的可获得性和水分条件。研究小组将量化土壤中沉积的凋落物数量，测量土壤碳和磷分数、氮矿化、土壤剖面、土壤蒸渗仪和溪水中的铁、铝和pH值。将评估微生物的活性，同时还将针对与大分子碳水化合物降解和氮磷循环相关的基因表达。通过Illumina HiSeq测序的转录本数据将被映射到预先存在的元基因组的组装支架上，并提供一种评估基因表达变化的方法。这项研究将提供第一个关于飓风效应的综合实验，以表征环境前后的条件和生物地球化学循环随土壤深度的变化，并跨越单一和重复的干扰。该小组还将率先采用微生物活性、转录组分的新分析，并在干扰和恢复的背景下将其与生物地球化学指标直接联系起来。

This research will study the immediate effects of Hurricane Maria on the dynamics of organic carbon and nutrients in a tropical forest and the streams draining that forest to better determine how short-term impacts affect the long-term trajectory of forest and water resources following single and repeated disturbances. Hurricane Maria led to widespread canopy damage and litter deposition on the soil surface and in stream channels within the Luquillo Experimental Forest (LEF) in Puerto Rico. Understanding how organic carbon, phosphorus, and nitrogen within plant detritus are modified during their movement through soils and into streams, including any exchanges with the atmosphere, is critical to determining long-term ecosystem response to disturbance. The research conducted as part of this project will provide insights into the resilience and resistance of the LEF ecosystem, part of the El Yunque National Forest in the US National Forest System. The PI team will work closely with scientists and students in Puerto Rico and facilitate local student and faculty research needs. The investigators will build the project results into a portfolio of presentations and outreach activities centered on the impacts of climate variability on terrestrial ecosystems. The project will promote diversity in science by supporting Puerto Rican students as laboratory personnel, providing training to other Hispanic students and post-doctoral scientists, and promoting gender equity in science through outreach and mentoring activities.This research makes use of a pre-existing hurricane simulation experiment allowing the researchers to test hypotheses about the effects of single and repeated hurricane disturbance on ecosystem processes, including biogeochemical translocations of carbon and nutrients through soil profiles and microbial activities in response to substrate availability and moisture conditions. The research team will quantify the amount of litter deposited on the soil, measure soil carbon and phosphorus fractions, nitrogen mineralization, iron species, aluminum, and pH in soil profiles, soil lysimeters, and stream water. Microbial activity will be assessed while also targeting gene expression related to macromolecular carbohydrate degradation and nitrogen and phosphorus cycling. Transcript data sequenced via Illumina HiSeq will be mapped to assembled scaffolds from pre-existing metagenomes and provide a means of assessing changes in gene expression. The research will provide the first comprehensive experiment of hurricane effects that characterizes the pre- and post-environmental conditions and biogeochemical cycling with soil depth, and across single and repeated disturbances. This group will also be the first to employ novel analyses of microbial activity, transcriptomics, and link this directly with biogeochemical indices in the context of disturbance and recovery.